Morning walk through the commons during the summer is a great way to start the day
Boston is not known for great Chinese food (an accurate description, more or less), but it has a few great Taiwanese spots scattered throughout the city. Taiwan Cafe is one of them.
Boston Sailing Center
A relaxing afternoon in the summer could be spent sailing on the Charles River - gorgeous views throughout.
The North End
Visit Boston's historic North End - its tiny cobblestone streets, the various historic tours happening throughout, and the general feeling stepping back into the pre-Revolutionary days of this city.
Best canolis in Boston. Get the chocolate chip.
Tucked away in South End, Toro is one of the most underrated and unpretentious (and yet ridiculous delicious) spots in Boston. Their tapas are absolutely mouth-watering. They don't take reservations though - so make sure to go early, or go late, to avoid the wait.
Middle East Upstairs
Across the river in Central Square, Middle East hosts live band performances a few nights a week. A great way to sit back and check out some of the local artists in the area.
Myung Dong 1st Ave
Take the green line past BU out to Allston, and you'll find this Korean "watering hole" of sorts, full of character and a delicious variety of soju.
I would stay at: The Liberty Hotel, Boston
A prison back in the day, the Liberty has been re-built into a very modern, spacious hotel on the water with a great bar area (often filled with doctors, businesspeople, and general young/not-too-young professionals of the city).